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51.
52.
Heckman D. Williams J. Robertson W. Emond A. 《IEEE transactions on aerospace and electronic systems》1974,(4):458-470
Shock waves originating from hypersonic projectiles flown in ballistic ranges and subsequently reflected from the range walls have been found to produce undesirable effects on the measurements of projectile wakes. This paper reports on the mechanisms through which reflected shock waves perturb the wake, the design, and installation of full-scale fiberglas wedge shock attenuation treatments, the design of equipment for minimum shock reflection, and the results of measurements of the performance of the treatment. 相似文献
53.
Allen J.J. Kinney R.D. Sarsfield J. Daily M.R. Ellis J.R. Smith J.H. Montague S. Howe R.T. Boser B.E. Horowitz R. Pisano A.P. Lemkin M.A. Clark W.A. Juneau T. 《Aerospace and Electronic Systems Magazine, IEEE》1998,13(11):36-40
Electronic sensing circuitry and micro-electro-mechanical sense elements can be integrated to produce inertial instruments for applications unheard of a few years ago. This paper describes the Sandia M3EMS fabrication process, inertial instruments that have been fabricated, and the results of initial characterization tests of micro-machined accelerometers 相似文献
54.
J. Kissel K. Altwegg B. C. Clark L. Colangeli H. Cottin S. Czempiel J. Eibl C. Engrand H. M. Fehringer B. Feuerbacher M. Fomenkova A. Glasmachers J. M. Greenberg E. Grün G. Haerendel H. Henkel M. Hilchenbach H. von Hoerner H. Höfner K. Hornung E. K. Jessberger A. Koch H. Krüger Y. Langevin P. Parigger F. Raulin F. Rüdenauer J. Rynö E. R. Schmid R. Schulz J. Silén W. Steiger T. Stephan L. Thirkell R. Thomas K. Torkar N. G. Utterback K. Varmuza K. P. Wanczek W. Werther H. Zscheeg 《Space Science Reviews》2007,128(1-4):823-867
The ESA mission Rosetta, launched on March 2nd, 2004, carries an instrument suite to the comet 67P/Churyumov-Gerasimenko. The COmetary Secondary Ion Mass Anaylzer – COSIMA – is one of three cometary dust analyzing instruments onboard Rosetta. COSIMA is based on the analytic measurement method of secondary ion mass spectrometry (SIMS). The experiment’s goal is in-situ analysis of the elemental composition (and isotopic composition of key elements) of cometary grains. The chemical characterization will include the main organic components, present homologous and functional groups, as well as the mineralogical and petrographical classification of the inorganic phases. All this analysis is closely related to the chemistry and history of the early solar system. COSIMA covers a mass range from 1 to 3500 amu with a mass resolution m/Δm @ 50% of 2000 at mass 100 amu. Cometary dust is collected on special, metal covered, targets, which are handled by a target manipulation unit. Once exposed to the cometary dust environment, the collected dust grains are located on the target by a microscopic camera. A pulsed primary indium ion beam (among other entities) releases secondary ions from the dust grains. These ions, either positive or negative, are selected and accelerated by electrical fields and travel a well-defined distance through a drift tube and an ion reflector. A microsphere plate with dedicated amplifier is used to detect the ions. The arrival times of the ions are digitized, and the mass spectra of the secondary ions are calculated from these time-of-flight spectra. Through the instrument commissioning, COSIMA took the very first SIMS spectra of the targets in space. COSIMA will be the first instrument applying the SIMS technique in-situ to cometary grain analysis as Rosetta approaches the comet 67P/Churyumov-Gerasimenko, after a long journey of 10 years, in 2014. 相似文献
55.
Immunolocalization of an annexin-like protein in corn. 总被引:4,自引:0,他引:4
G B Clark M Dauwalder S J Roux 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(8):341-346
Although calcium has been proposed to be an important regulatory element in plant gravitropic growth, as yet no specific function of Ca2+ in growth regulation has been discovered. Our recent studies on a Ca(2+)-binding protein in pea seedlings called p35 indicate that it is a member of the annexin family of proteins and may play a key role in growth regulation through its function in delivering polysaccharides needed for wall construction. We previously reported the isolation of p35 from pea plumules and the production of polyclonal antibodies to it. Immunolocalizaton analyses of p35 in pea tissues revealed high levels of staining in secretory cell types such as developing vascular cells and outer root cap cells. To test how general was the occurrence and distribution of this annexin-like protein in plant cells we initiated an analysis of annexins in the monocot corn using immunological techniques. Our results indicate the immunochemical properties and localization of corn annexins are very similar to those reported for pea. They are consistent with the postulate that annexins may play a general role in the regulation of the secretion of wall polysaccharides needed for growth, and thus could be an important target of calcium action during gravitropic growth. 相似文献
56.
J Chen D Chenette R Clark M Garcia-Munoz T G Guzik K R Pyle Y Sang J P Wefel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):765-769
The galactic cosmic rays (GCR) contain fully stripped nuclei, from Hydrogen to beyond the Iron group, accelerated to high energies and are a major component of the background radiation encountered by satellites and interplanetary spacecraft. This paper presents a GCR model which is based upon our current understanding of the astrophysics of GCR transport through interstellar and interplanetary space. The model can be used to predict the energy spectra for all stable and long-lived radioactive species from H to Ni over an energy range from 50 to 50,000 MeV/nucleon as a function of a single parameter, the solar modulation level phi. The details of this model are summarized, phi is derived for the period 1974 to present, and results from this model during the 1990/1991 CRRES mission are presented. 相似文献
57.
The Global Geospace Science (GGS) WIND and POLAR spacecraft employ unique configuration and design features driven by the requirements of the science instruments which they host. The WIND and POLAR spacecraft are cylindrically shaped spinners (WIND 20 rpm, POLAR 10 rpm) approximately 2.4 m in diameter and 1.8 m high. Each spacecraft has a pair of lanyard booms, which hold magnetometers, four radial wire antennas and two spin-axis antennas. While satisfying different mission requirements, both share a common basic design. The WIND laboratory contains 8 instruments, designed to optimize measurements of waves, fields and particle distributions. The POLAR laboratory contains 12 instruments, with a similar design emphasis on waves, fields and particle measurements, as well as on auroral imaging. The main difference between the two spacecraft is a despun platform on POLAR which provides a stable environment for the auroral imager instruments. Both laboratories are designed to be launched on Delta II model 7925 launch vehicle and have total masses of approximately 1150 g (WIND) and 1240 kg (POLAR). 相似文献
58.
S. A. Fuselier P. Bochsler D. Chornay G. Clark G. B. Crew G. Dunn S. Ellis T. Friedmann H. O. Funsten A. G. Ghielmetti J. Googins M. S. Granoff J. W. Hamilton J. Hanley D. Heirtzler E. Hertzberg D. Isaac B. King U. Knauss H. Kucharek F. Kudirka S. Livi J. Lobell S. Longworth K. Mashburn D. J. McComas E. Möbius A. S. Moore T. E. Moore R. J. Nemanich J. Nolin M. O’Neal D. Piazza L. Peterson S. E. Pope P. Rosmarynowski L. A. Saul J. R. Scherrer J. A. Scheer C. Schlemm N. A. Schwadron C. Tillier S. Turco J. Tyler M. Vosbury M. Wieser P. Wurz S. Zaffke 《Space Science Reviews》2009,146(1-4):117-147
The IBEX-Lo sensor covers the low-energy heliospheric neutral atom spectrum from 0.01 to 2 keV. It shares significant energy overlap and an overall design philosophy with the IBEX-Hi sensor. Both sensors are large geometric factor, single pixel cameras that maximize the relatively weak heliospheric neutral signal while effectively eliminating ion, electron, and UV background sources. The IBEX-Lo sensor is divided into four major subsystems. The entrance subsystem includes an annular collimator that collimates neutrals to approximately 7°×7° in three 90° sectors and approximately 3.5°×3.5° in the fourth 90° sector (called the high angular resolution sector). A fraction of the interstellar neutrals and heliospheric neutrals that pass through the collimator are converted to negative ions in the ENA to ion conversion subsystem. The neutrals are converted on a high yield, inert, diamond-like carbon conversion surface. Negative ions from the conversion surface are accelerated into an electrostatic analyzer (ESA), which sets the energy passband for the sensor. Finally, negative ions exit the ESA, are post-accelerated to 16 kV, and then are analyzed in a time-of-flight (TOF) mass spectrometer. This triple-coincidence, TOF subsystem effectively rejects random background while maintaining high detection efficiency for negative ions. Mass analysis distinguishes heliospheric hydrogen from interstellar helium and oxygen. In normal sensor operations, eight energy steps are sampled on a 2-spin per energy step cadence so that the full energy range is covered in 16 spacecraft spins. Each year in the spring and fall, the sensor is operated in a special interstellar oxygen and helium mode during part of the spacecraft spin. In the spring, this mode includes electrostatic shutoff of the low resolution (7°×7°) quadrants of the collimator so that the interstellar neutrals are detected with 3.5°×3.5° angular resolution. These high angular resolution data are combined with star positions determined from a dedicated star sensor to measure the relative flow difference between filtered and unfiltered interstellar oxygen. At the end of 6 months of operation, full sky maps of heliospheric neutral hydrogen from 0.01 to 2 keV in 8 energy steps are accumulated. These data, similar sky maps from IBEX-Hi, and the first observations of interstellar neutral oxygen will answer the four key science questions of the IBEX mission. 相似文献
59.
A. H. Manson C. E. Meek M. Massebeuf J. L. Fellous W. G. Elford R. A. Vincent R. L. Craig A. Phillips R. G. Roper G. J. Fraser M. J. Smith S. Avery B. B. Balsley R. R. Clark S. Kato T.Tsuda R. Schminder D. Kuerschner 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1990,10(12):267-315
60.
The communications and tracking (C&T) system on board the orbiting platform communicates with the ground facilities through the TDRS satellites. The C&T system operates on Ku and S-band. Using a high gain antenna the Ku-band channel can support a downlink data rate of 300 Mbps through the TDRS single axis channel. The S-band system communicates with the orbiter and with both multiple and single axis TDRS channels. The Data Management System (DMS) provides the following services to the orbiting platform: data distribution within and between core systems and payloads, data processing facilities for core systems, data base management, time and frequency standards, and overall platform management and control. The DMS is a distributed data processing network. The nodes are connected by a local area network (LAN). Each node is autonomous. Since the design is modular, nodes can be added or deleted without disturbing the system. Sensors and effectors communicate with the core system software via the network through multiplexers/demultiplexers. 相似文献